Girk' T'ght'ots' [The Book of Letters] (Tiflis, 1901) in Classical Armenian. A collection of documents dating from the 5th-13th centuries concerning theological, Christological and dogmatic matters. Letters to and from heads and senior clerics of the Armenian Apostolic Church and neighboring Churches. An invaluable historical source (pdf format). Book digitized by Google and uploaded by Robert Bedrosian.